Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 50,788	$ 68,454
Marketable securities	412,180	445,733
Prepaid expenses	7,701	6,718
Other current assets	5,113	11,825
Total current assets	475,782	532,730
Property and equipment, net	10,141	2,870
Operating lease right-of-use assets	8,110
Intangible assets	102,500	102,500
Goodwill	6,234	6,234
Other noncurrent assets	1,850	3,997
Total assets	604,617	648,331
Current liabilities:
Accounts payable	3,012	7,989
Accrued and other current liabilities	20,946	18,086
Deferred revenue, noncurrent	6,027	0
Current portion of operating lease liabilities	1,402
Current portion of contingent consideration	34,800	32,300
Total current liabilities	66,187	58,375
Deferred revenue, noncurrent	8,404	0
Operating lease liabilities, net of current portion	11,186
Contingent consideration, net of current portion	35,700	45,900
Deferred income taxes	17,425	17,425
Other long-term liabilities	0	3,830
Total liabilities	138,902	125,530
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000 shares authorized; none issued and outstanding	0	0
Common stock, $0.001 par value; 100,000 and 50,000 shares authorized and 42,498 and 42,078 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	42	42
Additional paid-in capital	1,233,866	1,218,710
Accumulated deficit	(768,919)	(695,954)
Accumulated other comprehensive income	726	3
Total stockholders’ equity	465,715	522,801
Total liabilities and stockholders’ equity	$ 604,617	$ 648,331